1. Field
The present invention relates to a vehicle drive unit and relates particularly to a vehicle drive unit having an electric motor and reduction gearing installed inside a wheel hub of a vehicle.
2. Description of Related Art
Patent Document 1 (Japanese Patent Application Publication No. 2005-335535) discloses a hub unit for an electrically movable wheel having an electric motor and reduction gearing arranged inside a wheel hub of an electric vehicle as a drive unit of the vehicle. This hub unit includes a left-right split type shaft formed of a rotating shaft which is a motor output shaft and left and right fixing support shafts provided at both ends of the rotating shaft. The left fixing support shaft is fixed to a holding plate (first end plate) rotationally supporting the wheel. The right fixing support shaft is supported on a boss formed on a support frame for planetary gears forming the reduction gearing. The shaft of each planetary gear included in the reduction gearing disposed inside a right part of the hub unit is supported on a carrier (second end plate) of the planetary gear and the support frame.
In the hub unit for an electrically movable wheel described in Patent Document 1, the right fixing support shaft is supported by means of only the support frame fixed to the carrier. Thus, the right fixing support shaft is supported based on the strength of the support shaft. The support structure for the fixing support shaft is desirably capable of supporting it more firmly because the weight of the vehicle and the rider during travel is exerted as a load on the fixing support shaft. The strength may be improved by increasing the size of the support frame. However, it has a problem that there is a limitation in increasing the size of the lid member disposed in the wheel hub which is a limited space. Moreover, centering the split axles is difficult because multiple extension parts supporting the axles lie therebetween.